11 Animal Wonders of Evolution

The evolution of life has not been an orderly affair. Every time a biological age is swept aside, a few creatures remain. Millions of years later, many are still with us.

Sometimes these animals are called "living fossils," but it's not a good term. After all, their lineages haven't survived ice ages and warm spells and every natural upheaval just to be visualized in amber by some upstart hairless ape. A better term is "evolutionarily distinct." They're simply, impressively unique.

"Evolutionarily distinct creatures contain more genetic diversity. They look different. They tend to be behaviorally different. These are species that are different from everything else on the planet," said Jonathan Baillie, conservation program director at EDGE of Existence.

EDGE stands for Evolutionarily Distinct and Globally Endangered, which are the criteria of the animals it tries to protect. They're not just singularly unique, but desperately imperiled and often unappreciated: Pangolins and purple frogs and Laotian rock rats don't have the charisma of traditional conservation favorites, yet in some ways they're more important. To use an art world analogy, losing an EDGE species isn't like losing a Renoir or Monet, but the entirety of French Impressionism.

"We've grown up with rhinos and tigers and lions on TV. Our generation is quite familiar with those. It's now possible expand conservation beyond that," said Baillie. "By conserving EDGE creatures, you save a disproportionate amount of genetic, ecological and behavioral diversity."

On the following pages, Wired.com takes a tour of our favorite EDGE animals.

The modern descendants of a lineage that can be traced to the dawn of modern mammals, tarsiers are the smallest known primates. Adapted for hunting insects and other invertebrates in nighttime forests, their heads can rotate almost 360 degrees, and their eyes can outweigh their brains.

Image: Geoff Deehan

Kha-Nyou

Until biologists found several at a Laotian food market, Kha-Nyou — less prettily known as Laotian rock rats — were thought to have gone extinct 11 million years ago, along with the rest of their taxonomic family.

Genetic analyses show that they last shared a common ancestor with any living species 44 million years ago.

Sunda Pangolin

Covered in scales made of keratin, the material from which fingernails are made, pangolins split off from edentates — the order containing sloths, anteaters and armadillos — 60 million years ago. Any features they share with anteaters are the result of convergent evolution, with natural selection and adaptation arriving at similar traits in unrelated animals.

There are seven species of pangolin. One of the rarest is the Sunda pangolin. "When I first saw one, I was in Laos, on a boat. A woman put this bag in the boat. It was quite heavy. She said, I want $5 for it," said Baillie. "They're phenomenal creatures. Magical. Absolutely wonderful."

Asian Tapir

Of the four species of tapir, the Asian Tapir most closely resembles those that lived 50 million years ago, at the root of an evolutionary branch that later sprouted horses and rhinoceros, their closest relative.

Their fleshy snouts, however, are believed to be a relatively recent adaptation.

Hispaniola Solenodon

"They are truly ugly creatures," said Baillie of the solenodons, a family of venomous, shrew-like insectivores that split 76 million years ago from all other mammals. Today there are two species: the Cuban Solenodon, found in Cuba, and the Hispaniola Solenodon, found in Haiti.

"They're part of a faunal group that evolved quite separately from both North and South America," Baillie said. "You had rodents the size of horses, a really unique animal mammal community. But with the colonization of those islands, most of those species disappeared. We're left with very few representatives."

Image: Wikimedia Commons

Duck-Billed Platypus

The undisputed champion of mammalian evolutionary distinctiveness, duck-billed platypuses are the last living members of a family that originated 150 million years ago. The Australian egg-layers are so odd that some scientists have considered them reptiles.

Image: National Human Genome Research Institute

Chinese Giant Salamander

While EDGE of Existence started their conservation efforts with mammals, they've since moved on to amphibians.

The largest of all amphibians is the Chinese giant salamander, which can reach lengths of 6 feet and weigh 100 pounds. Its origins date to 50 million years ago, though its ancestors were just a fraction of its size.

Image: Wikimedia Commons

Archey's Frog

Virtually unchanged in 150 million years, and belonging to a line that split 200 million years ago from other toads and frogs, this primitive resident of New Zealand even predates the existence of birds.

Archey's frogs have muscles for a long-lost tail, but no eardrums: Rather than communicating with sound, they use scent. They're also an EDGE success story, with conservationists' attention helping to delay mining plans in the frogs' mountain habitat.

Okarito Kiwi

In coming years, EDGE of Existence will expand to include birds. Though full phylogenetic comparisons still need to be completed, it's safe to say that kiwis will place near the top of the list.

The smallest of the ratites, a group that includes ostriches and emus, these flightless birds evolved without predators for millions of years. With the introduction of cats and dogs to Australasia, that's no longer the case.

Rarest of all New Zealand's kiwis is the Okarito kiwi, discovered in 2003 and numbering about 350 birds. Capable of living for a century, they're following in the footsteps of the dodo.

"We're entering a period of mass extinction. We will lose a lot of species," said Baillie. "It's essential to make sure that these creatures, so different from all species on the planet, don't get lost without us even noticing."